I wanna get a yellow top unther "tha hood" and I wanna replace the normal (original) battery to the back of the car, now I'm not realy sure how to connect it...I don't wanna bring 24v to my car...do I connect it like 1 or 2 in the picture? and do I need to put something between the 2 batteries (regulator...or a diode or something?)???

I hope someone can help me out here...

thanks

Option 1 will b very interesting when you connect it up. Pretty sparks and all. Also may weld what ever the last connecter is that you connect together.
(BTW- thats not 24v. Thats 0v)

Option 2 - nothing special there. Check out some of the 4x4's. (Mitsibushi Pajero's (gotta luv jappa cars) as far as i know do this. I also think Toyota landcruisers do as well).

I am looking forward to your setup Danon, since this setup is used in campers hee in Belgium this setup can't be that bad, is it ?

ok here it is...

first of all the idea is this (i may not be 100% accurate on the small things as i had this setup for quite some time now, if you found some plz. inform me. also i made this possible with the help of robiewp, another member):

1. tank batt. will be only connected to car batt. if the engine is running (for charging).

2. and if the engine is not running, unless i turned on car key to acc. the two batt. should not be connected to each other.

...your 2nd batt. should be deepcycle as it is designed to be drained and charged again and again. the normal car batt. is made only to crank an engine.

since i don't have a solenoid or diode, i control the relay manually, check the pics, it is in the middle of the 3 socket cig. lighter, remember, 2 batt. in parallel always goes equilibrium when connected. if your 2nd batt is very low while running the car and you stop on red light and your main batt is below 13.5v, your engine will hesitate. if you're on an uphill it may even stop, so some kind of relay cutoff is very important.

i can't use diode for two reasons: first it reduces voltage comming in and 2nd bec. of the high amperage involve.

rather than spending money on some very expensive off-the-shelve technology, i spend more on research and ideas. i have found a small kit that signals when voltage goes low. i can use it to control the relay so when main batt goes low to say 13.5 (in my case) it will cut the supply of +12v to the relay, therefore cutting off the supply of power to the 2nd (tank) batt.

I wanna get a yellow top unther "tha hood" and I wanna replace the normal (original) battery to the back of the car, now I'm not realy sure how to connect it...I don't wanna bring 24v to my car...do I connect it like 1 or 2 in the picture? and do I need to put something between the 2 batteries (regulator...or a diode or something?)???

I hope someone can help me out here...

thanks

Actually i would suggest placing the yellow top in the back of the car, and leaving the regular battery under the hood. Lead-acid batteries are supposed to be kept out of areas that are closed and exposed to people. The yellow top is sealed, and much safer. Once the batteries are in parallel it no longer matters where they are in the car electrically.

I'm running a second battery in mine and it works fine. Mounted an isolator under the existing battery and the voltage sense wire for my alternator feeds off of the main battery so it compensates for the .7v drop of the isolator diodes.

rather than spending money on some very expensive off-the-shelve technology, i spend more on research and ideas. i have found a small kit that signals when voltage goes low. i can use it to control the relay so when main batt goes low to say 13.5 (in my case) it will cut the supply of +12v to the relay, therefore cutting off the supply of power to the 2nd (tank) batt.

danon

as far as i can gather, the problem is not really when the main battery low.
its when the 2nd battery low and main battery full - then it charges too fast and nasty stuff happening.

as far as i can gather, the problem is not really when the main battery low.
its when the 2nd battery low and main battery full - then it charges too fast and nasty stuff happening.

there are different type of battery chargers with varying amps for charging the same battery. go figure.

also if you put a volt meter to your main battery to monitor the charging and do a typical city drive, you will notice that voltage flactuates from within 11.9 to 14.5 (depends on your extra acc.) it goes high as the alternator charges the battery, and then goes low when the car slowsdown or idle on stoplights. all this flactuations happens from within split seconds. even when your not driving, everytime you rev your engine, you are also charging your battery too fast.

So, I would be safe using just a standard 30 Amp relay to control my yellow top charging? I thought I needed something much more heavy duty. And how heavy does the wire need to be? I was thinking I needed something like 2 AWG or heavier. If I only need a standard relay, I could start installing this thing now.